1 / 32

Zhe Xu

Johann Wolfgang Goethe-Universität Frankfurt Institut für Theoretische Physik. Parton Thermalization and Energy Loss in ultrarelativistic Heavy-Ion Collisions within a Parton Cascade. Zhe Xu. in collaboration with A. El, O.Fochler and C.Greiner. QM2006, Shang Hai. Motivation.

jameson-dickerson
Download Presentation

Zhe Xu

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Johann Wolfgang Goethe-Universität Frankfurt Institut für Theoretische Physik Parton Thermalization and Energy Loss in ultrarelativistic Heavy-Ion Collisions within a Parton Cascade Zhe Xu in collaboration with A. El, O.Fochler and C.Greiner QM2006, Shang Hai

  2. Motivation • fast thermalization • on-shell parton cascade Z. Xu and C. Greiner, PRC 71, 064901 (2005) • with only pQCD gg<->gg : no thermalization except with large s (AMPT,MPC) • including pQCD gg<->ggg: thermalization, hydro. behaviour and Jet-Quenching

  3. What is the correct quantity describing kinetic equilibration? • NOT the mean free path or collision rate ns • maybe nst with the transport cross section gg -> gg gg -> ggg B.Müller‘s question in Quark Matter 2005 One has to do detailed studies.

  4. momentum isotropization and kinetic equilibration Initial condition: Minijets p0=1.4 GeV

  5. q(t) gives the timescale of kinetic equilibration.

  6. Transport Rates Definition: Boltzmann equation

  7. The drift term is large.

  8. special case for isotropic distribution of collision angle

  9. Bremsstrahlung processes J.F.Gunion, G.F.Bertsch, Phys. Rev. D 25, 746(1982) LPM suppression: the formation time Bethe-Heitler regime

  10. Initial condition with Color Glass Condensate h: [-0.05:0.05] and xt < 1.5 fm

  11. Evolution of Particle Number in bottom-up scenario Andrej El • Particle number decreases rapidly in the very first moment • No net soft gluon production at early times!

  12. Jet-Quenching in a central Au Au collision at RHIC Oliver Fochler 3~4 too much

  13. elliptic flow in noncentral Au+Au collisions at RHIC: peripheral central

  14. Summary • PQCD Bremsstrahlung gg↔ggg are essential for the thermalization. • The transport rates are quantities determining the contribution of different processes to kinetic equilibration. • no bottom –up • large v2, but small RAA

  15. Minijets p0=1.4 GeV

  16. q(t)

  17. Simulation 1 Simulation 2 thermalization and hydrodynamical behavior NO thermalizationand free streaming Question: Why are gg<->ggg interactions essential for thermalization?

  18. P.Danielewicz, G.F.Bertsch, Nucl. Phys. A 533, 712(1991) A.Lang et al., J. Comp. Phys. 106, 391(1993) Stochastic algorithm cell configuration in space D3x for particles in D3x with momentum p1,p2,p3 ... collision probability:

  19. Initial conditions: minijets production with pt > p0 binary approximation  for a central Au+Au collision at RHIC at 200 AGeV using p0=2 GeV

  20. Initial conditions with smaller p0

  21. Kinetic and chemical equilibration in the central region: h: [-0.5:0.5] and xt < 1.5 fm 1~2 fm/c for the kinetic equilibration ~ 4 fm/c for the chemical equilibration

  22. Kinetic and chemical equilibration

  23. transverse energy at y=0 in Au+Au central collision

  24. Kinetic and chemical equilibration

More Related